The eigenvalues of \(M_w\) , that is, the effective masses in matter, are
given by [1]}, [2]}
\(\mu ^2_{1,2}=\frac{m_1^2+m_2^2}{2}+E(V_e+V_a)\mp \frac{1}{2}\sqrt{(\Delta m^2\cos 2\theta -A)^2+(\Delta m^2\sin 2\theta )^2},\) 
